Anti-halation layer for silver halide light-sensitive materials



United States Patent 1m. 01. Gll3c 1/84 US. Cl. 96-84 16 Claims ABSTRACTOF THE DISCLOSURE Silver halide light-sensitive material comprising asupport, at least -one silver halide emulsion layer and an anti-halationlayer, said anti-halation layer consisting of a hydrophilic colloidlayer having incorporated therein a polymer containing more than 50percent of Z-methyll-vinylamidazole and a dyestufi having an acid group.

This invention relates to a photographic silver halide light-sensitivematerial having a layer containing a dyestuflf resistant to difiusionfor preventing the formation of halation.

It is well known that in photographic light-sensitive materials, thesharpness of the image is increased by preventing the formation ofhalation at exposure. Various methods have been provided for preventingthe formation of halation. For example, there has generally beenemployed a method in which a layer for absorbing the light effective forsensitization is placed between a light-sensitive layer and a support, amethod in which a material for absorbing such light is incorporated inthe support, and a method in which such an absorbing layer is formed onthe surface of the support opposite to the light-sensitive layer. Theabove-mentioned first and second methods are most effective for theprevention of the formation of halation. However, there are difiicultiesin the first method in that the material for absorbing the eflfectivelight has been diffused from the intermediate layer into thelight-sensitive layer. This reduces the sensitivity and gradation of thelightsensitive layer. Also, if the material has not been diffused out ofthe intermediate layer, it remains in the layer after developing fixingand water-washing have been completed. This results in darkening of theformed image. Further, the second method can be used for only a limiteduse since the absorbing material remains, in general, in the supportafter processing.

These difficulties accompanying the application of the first method orthe second method may be overcome in accordance with the abovedescribedthird method, but the presence of a comparatively thick support layerbetween the light-sensitive layer and the anti-halation layer reducesthe anti-halation effect of the layer itself.

Accordingly, it is most preferable that in the first method theabsorbing material is not present in the light-sensitive layer bydiffusion before exposure and the material will be removed from theintermediate layer by diffusion or decolored by a chemical action atdevelopment after exposure. As an example of such improvements, the useof a colloidal silver particle has been proposed but while it is usedeffectively for color photographic materials, it cannot be effectivelyused for black and white photo- 3,445,231 Patented May 20, 1969 "icegraphic materials. Hence, in order that such means be used for black andwhite photographic materials, the use of dyestuffs instead of the use ofcolloidal silver is desirable.

Therefore, an object of this invention is to provide an anti-halationlayer containing therein a dyestufi capable of asborbing light effectiveto sensitization, wherein the diffusion of the dyestuif into thelight-sensitive layer before exposure is kept as small as possible,after the antihalation layer is coated on the light-sensitive layer andthe dyestuif is easily decolored by the developing, fixing andwater-washing treatments after exposure.

This object can be achieved by using as the anti-halation layer a layerof a hydrophilic colloid, such as gelatin, containing (1) a polymercomposed of more than 50% of 2- methyl-l-vinylimidazole and (2) adyestutr' having an acid group. If the content of2-rnethyl-1-vinylimidazole in the polymer is less than 50%, the polymeris ineffective for the present invention.

As the light-sensitive layer to which the anti-halation layer of thisinvention is utilized, a silver halide photographic emulsion layer canbe used and particularly a photographic silver halide emulsionsensitized optically and having a high resolving power can be profitablyused.

On practicing this invention, after applying an under coating to thesurface of a film support composed of a high-molecular material, suchas, triacetyl cellulose or polyethylene terephthalate to provide anadhesive power to a hydrophilic colloid layer such as a gelatin layer,the anti-halation layer of this invention is applied to thus treatedfilm and on the anti-halation layer is applied a silver halidephotographic emulsion layer and, if necessary, a protective layer. Inthis invention, further, a paper may be used as the support.

In order to facilitate the application of a photographic silver halideemulsion layer to the anti-halation of this invention, the anti-halationlayer may contain various surface active agents, such as sap'onin,sodium alkylbenzene sulfonate, polyoxyethylene alkylphenyl ether and thelike.

The gelatin used in this invention may be one prepared by lime-treatingor acid-treating a raw material, such as oxhides, ox bones, and pighides.

For increasing the strength of the film, a hardening agent, such asformaldehyde, mucochloric acid, chlorotriazine derivatives, and the likemay be used and moreover, a hardening acid, such as resorcinol, resorcylaldehyde and the like may be used together with the hardening agent.

Further, a stabilizer for photographic emulsion, such as4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene, etc., may be added in theanti-halation layer of this invention to increase the photographicproperties of the emulsion layer.

Furthermore, a low-sensitive photographic silver halide emulsion may bedispersed in the anti-halation layer of this invention to improve thegradation of the lightsensitive material.

Still further, the anti-halation layer in this invention may be used asthe intermediate layers for each light-sensitive layer of a multi-layercolor photographic material to prevent the formation of halation in theupper layers and at the same time to suppress undesirable opticallysensitive areas in the lower layers.

A suitable amount of dyestuff used in this invention is 1 to 20 g. perg. of dried gelatin and that of the polymer is 2 to 40 g. per 100g. ofdried gelatin.

' The following examples of thepractical dyestuffs used in thisinvention, the examples for the synthesis of the polymers used in thisinvention and the examples of this invention will serve to understandthis invention in detail, but it should be understood that the inventionis not limited to the examples.

Typical examples of the dyestufis used in this invention are as follows:

'Dyestufi 9 7 Se\ Gin Se o=on- ';=oH-o N/ N ornomomsoma onlomonlsorTypical examples of the dyes used in this invention were shown above,-but it should be understood that dyes of this invention shall not belimited to these compounds, but may be ones containing acid groups, suchas a' sulfonate group and carboxylate group, which are decolored duringprocessing.

The following are the practical examples for synthesizing the polymersused in this invention.

Synthesis l.In 500 ml. of methanol was dissolved 150 g. of2-methyl-1-vinylimidazole, and after the addition of 0.3 g. ofazobis-isobutylonitril, the mixture was stirred for 3 hours at 60 C. ina nitrogen stream. After the end of reaction, 500 ml. of acetone wasadded into the reaction product and the mixture was poured in anexcessive amount of ether with stirring, whereby g. ofpoly-2-methyl-l-vinylimidazole was precipitated.

Synthesis 2.Into 700 ml. of water were dissolved 200 g. of2-methyl-1-vinylimidazole and 1 g. of sodium bisulfate and then asolution of l g. of potassium persulfate in 100 ml. of water was addedinto the solution with stirring in a nitrogen stream. The mixture wasstirred for 4 hours at 35 C., subjected to dialysis in a water streamfor one night, and dried by freezing to provide 190 g. of poly-2-methyl-l-vinylimidazole.

Synthesis 3.-Into 70 ml. of water were dissolved 31 g. of2-methyl-l-vinylimidazole, 9 g. of acrylamide and 0.2 g. of potassiumpersulfate, and after adding a solution of 0.2 g. of sodium bisulfate in10 ml. of water, the mixture was stirred from 3 hours at 40 C. in anitrogen stream. The solution was subjected to dialysis in a waterstream for one night and then to drying by freezing to provide 35 g. ofthe copolymer.

Synthesis 4.Into an aqueous solution of 35% isopropyl alcohol weredissolved 66.2 g. of 2-methyl-lvinylimidazole and 33.8 g. ofN-ethoxymethyl acrylamide to make the whole volume 500 ml. and after theaddition of 2 ml. of 30% hydrogen peroxide solution and 0.5 g. ofL-ascorbic acid, the mixture was stirred for 5 hours at 40 C. in anitrogen stream. The solution was subjected to dialysis in a waterstream for one night and dried by freezing to provide 85 g. of thecopolymer.

Synthesis 5 .-Into ml. of water were dissolved 25.5 g. of2-methyl-l-vinylimidazole, 14.5 g. of acryloylmorpholine, and 0.2 g. ofpotassium persulfate and, after the addition of a solution of 0.2 g. ofsodium persulfate in 10 ml. of water, the mixture 'was stirred for 4hours at 40 C. in a nitrogen stream. The solution was subjected todialysis for one night in a water stream and dried by freezing to give27 g. of the copolymer.

Synthesis 6.Into 150 ml. of water were dissolved 28 g. of2-methyl-1-vinylimidazole, 12 g. of l-vinylpyrrolidone and 0.2 g. ofpotassium persulfate and, after the addition of a solution of 0.2 g. ofsodium bisulfate in ml. of water, the mixture was stirred for 4 hours at40 C. in a nitrogen stream. The solution was subjected to dialysis forone night and dried by freezing to provide 30 g. of the copolymer.

Synthesis 7.Into 150 ml. of water were dissolved 29 g. of2-methyl-l-vinylimidazole, 11 g. of N-methylol acrylamide, and 0.2 g. ofammonium persulfate and after the addition of a solution of 0.2 g. ofsodium bisulfate in 10 ml. of water, the mixture was stirred for 2 hoursat 40 C. in a nitrogen stream. The solution was subjected to dialysisfor one night in a water stream and dried by freezing to provide 30 g.of the copolymer.

Example 1 Into 50 ml. of an aqueous solution containing 5 g. of gelatin,0.1 g. of saponin, and 0.1 g. of mucochloric acid was added 8 ml. of a5% aqueous solution of the polymer obtained in Synthesis 1 and then wereadded the 2% aqueous solutions of Dyestufis 1, 4, and 6 in an amount of10 ml. each. After adjusting the pH of the solution to 6.5 with theaddition of sodium carbonate, the solution was added with water up to100 ml. (Sample A.)

As a comparative sample, the solution without containing the polymer wasprepared by the same procedure as above. (Sample B.)

Each of the above-prepared solutions was applied to a film base oftriacetyl cellulose having a colorless under coating in a driedthickness of 2 microns. A fine silver bromo-chloride particle emulsioncontaining 40 mol percent of silver chloride optically sensitized intopanchromatic state and gelatin in an amount of 120 g. per 1 mol of thesilver halide was applied onto the layer in a dried thickness of 2microns, and on thus formed layer was further applied a protective layerconsisting of gelatin and a hardening agent in a dried thickness of 1micron.

Further, for comparison, a sample consisting of a film base havingthereon only an emulsion layer and a protective layer was prepared.(Sample C.)

When thus prepared films using Samples A and B were treated with ausually available developing solution and fixing solution and thenwashed with water, the dyestuffs were easily decolored.

On the other hand, when the photographic sensitivities of the films werecompared, that of the film using Sample B was reduced to about 50% ofthat of Sample C, while that of the film using Sample A was reduced toonly 20% of that of Sample C. Further, it was confirmed that thesharpnesses of images in the films using Samples A and B were greatlyimproved as compared with that in Sample C. That is, by using Sample A,the sharpness could be increased with a smaller reduction insensitivity.

It was further confirmed by microscopic observation that in the case ofusing Sample A the dyestuif was scarcely ditfused into the emulsionlayer but in the case of using Sample B the dyestuff was markedlydiffused into the emulsion layer.

Example 2 The same procedure was repeated using 11 ml. of a 5% aqueoussolution of the polymer prepared in Synthesis 3 instead of the polymerin Example 1 and using 10 ml. each of the 2% aqueous solutions ofDyestuffs 2, 4, and 8. Almost in the same results as in Example 1 wereobtained.

Example 3 The same procedure as in Example 1 was repeated using 15 ml.of a 5% aqueous solution of the polymer prepared in Synthesis 6 insteadof using the polymer in Example 1 and using 10 ml., 8 ml., and 10 ml.each of the 2% aqueous solutions of Dyestuffs 2, 5, and 8 respectively.Almost the same results as in Example 1 were obtained.

Example 4 A coating solution was prepared as in Example 1 using 3 ml. ofan 0.1% aqueous solution of Dyestuif 9 instead of the aqueous solutionsof Dyestuffs l, 4, and 6 in Example l and the coating solution wasapplied to a redsensitive layer of a multi-layer type color photographicelement in a dried thickness of 1 micron. On the thus formed layer wereapplied a green-sensitive layer, a yellow colloidal silver layer,blue-sensitive layer and then a protective layer.

As comparative sample, a Sample A and a Sample B were preparedrespectively by applying a coating solution Dyestutf 9 but containing nopolymer on the red-sensitive layer of the color photographic element andby applying a coating solution containing neither Dyestutf 9 nor polymeron the red-sensitive layer. When these samples and the above preparedlight-sensitive material of this invention were treated by a standardcolor-reversal treatment, the color residue of the dyestulf was notobserved in each sample. On the other hand, it was found that theundesirable green-sensitivity of the red-sensitive layer of thelight-sensitive material of this invention was reduced to 50% ascompared with that of Sample B while the green-sensitivity of thered-sensitive layer of the lightsensitive material was reduced to only20%. Further, it was found that the red-sensitive layer and thegreensensitive layer of Sample A were reduced into 50% ingreen-sensitivity as compared with Sample B.

What we claim is:

1. A silver halide light-sensitive material comprising a support, atleast one silver halide emulsion layer and an anti-halation layer, saidanti-halation layer consisting of a hydrophilic colloid layer havingincorporated therein (1) a polymer containing more than 50% of2-methyl-1- vinylimidazole polymerized therein and (2) a dyestuif havinga salt of an acid group.

2. The silver halide light-sensitive material as claimed in claim 1wherein said dyestufif is one having the for- 3. The silver halidelight-sensitive material as claimed in claim 1 wherein said dyestulf isone having the for- SOaNa 4. The silver halide light-sensitive materialas claimed in claim 1 wherein said dyestufi is one having the forinclaim 1 wherein said dyestuff is one having the formula: mula:

HOOCfiC-CH=CHCH=CHCH=C-C-COOH SOaNa SOaNa N :0 0:0 N

5 HzN- (|3 NH: l I

so CH: I

S OaK SOaK NH:

9. The silver halide light-sensitive material as claimed in claim 1wherein said dyestnlf is one having the for- 5. The silver halidelight-sensitive material as claimed 5 mula: in claim 1 wherein saiddyestuif is one having the forso CH;(l3(l3HCH=CHCH=O-CCHa 0:0 o=0 N so10. The silver halide light-sensitive material as claimed 5 in claim 1wherein said dyestufi is one having the formula:

Se Se COONa OOONa 0,135

C=CH-C=CH--C 6. The silver halide light-sensitive material as claimed fIin claim 1 wherein said dyestutl is one having the for- 5 mula:HzCHaCHzSOaNa CHaCHaCHzSOa 11. The silver halide light-sensitivematerial as claimed in claim 1 wherein the amount of said polymer is 2to NaOOC-C CHCH=CHCH=CC-COONa g. per 100 g. of dried gelatin in saidanti-halation Q, =0 L layer and the amount of said dyestuff is l to 20g. per

\ 100 g. of the dyestuif.

N N 12. The silver halide light-sensitive material as claimed 40 inclaim 1 wherein said anti-halation layer is present between the silverhalide light-sensitive emulsion layer and an under coating for saidsupport.

13. The silver halide light-sensitive material as claimed in claim 1wherein said light-sensitive material is a multilayer type colorphotographic material and said anti-hala- 7. The silver halidelight-sensitive material as claimed figg i IS an mtermedlate layer foreach hght sensmve claim 1 Wherem Sald dyesmfi Is one havmg the 14. Thesilver halide light-sensitive material as claimed mula: in claim 1wherein said anti-halation layer further con- 60 tain a hardening agent.

15. The silver halide light-sensitive material as claimedCH;CCHOH=CHCH=CH=C-CCH; in claim 1 wherein said anti-halation layerfurther conn; tains a stabilizer.

\ 16. The silver halide light-sensitive material as claimed I I in claim1 wherein said anti-halation layer further contains a low-sensitivesilver halide particle.

References Cited UNITED STATES PATENTS son: soaK 2,182,794 12/1939Dawson.

NORMAN G. TORCHIN, Primary Examiner. 8. The silver halidelight-sensitive material as claimed J. R. HIGHTOWER, Assistant Examiner.

